Broaching tool



June 7, 1927.

G. H. RICHEY RoAcHING Toor.

Filed oct. 18. 192s invern/Zar.' rye llhv'wy.

ZZoi'W/egf Patented June 7, 1927.

UNITED STATES- PATENT OFFICE GEORGE E. EICHEY, or BosmonvMAssAcHUsEmrsASSIGNOE rre SULLIVANA MACHIN- Enry COMPANY, A eeRroEA'rioN 0EMASSACHUSETTS;

EEOAGHING l'rooL.

Application led October 1 8, 1926. Serial No. 142,482.

This inventionpertains to breaching tools, f

and more particularly to breaching tools of the impact type especiallyadapted for chan# a series of substantially equi-distantly rela-` tivelyclosely spaced holes are drilledin the rock by means of a usual hammerdrill alongv the line of the desired channel. Having produced therequired number of holes in the rock, it has been .founddesirable tobreach or break away the solid portion or partition of the rock betweenthe holes to form a con.- tinueus channel.` is substantially arepetition of the drilling operation 'witha breaching tool substitutedfor the usual `drill bit in the hammer drill. I-Ieretofore it has beenfound that `the breaching tools have a tendency to stick or bind in thehole, due to the dust or cuttings piling up in the hole around thebreaching tool.

Among theY objects of the present invention is to provide an improvedbreaching tool which will cut effectively. and wherein all tendencyofthe tool to stick lor bind in the hole is reduced to a minimum.Another object of this invention is to provide animand rugged characterwhich may be manu factured at a minimum of expense and which may besharpened with facility. Still another object of this invention'is toprovide an improved.breaching tool for break-- ingaway the partitions ofrock between a series of closely spaced drill holes, thus forming achannel. These and other objects will, however, hereinafter more fullyappear. er

In one embodiment the invention may be comprised in a breaching tool ofthe secalled bat wing type having a cylindrical r body portion adaptedto center and guide the breaching tool in the drill hole, and havinglaterally projecting double-tapered wings. The wings may have inclinedbottom cutting surfaces which are made flat to obtain a percussiveaction on the rock which the inventionf The breaching operation provedbreaching toolof exceedingly simple and the side edges of the cuttingsurface may be designed torperforma 'shearing action on the rock. Theiat side surfaces of the wings may be `tapered back from the cuttingedges to provide clearance while the wings may be of wedge shaped crosssection to prevent binding of lthe breaching tool in the drill hole. j

In the accoinpanying` drawing there is shown for purposes ofillustrationone form may; assume in practice. 1

In this drawinga y Fig. l is an elevationalview, partially broken awayin section, of a hammer rock drilling machine with which the improvedbreaching ltool is associated.

.Fig 2 is an enlarged front elevational view of the improved', breachingtool, the breaching tool being disposed in operative position in a drillhole while cutting a channel. i

Fig. 3 is an end elevational view of the breaching tool shown in Fig. 2.

Figa is aside elevational view of the breaching tool shown in Figs. 2and 3.

Fig. 5 is a diagrammatic view indicating several drill holes priorV tothe breaching operation.

Fig. 6 is a diagrammatic view illustrat ing 'the drill holes subsequentto the breaching operation. y

- `In `the. illustrative embodiment of the inventionthere is shown a.rock drill. of the hammer type generally designated l, herein of anystandard type having a usual cylinder 2 in which a hammerfpiston isreciprocable in the usual manner, the hammer piston having a forwardlyprojecting striking bar 3 which is adapted to impart a series of impactblows to a usual striking plug Ll. The impact blows of the hammer pistonare transmitted through the striking' plug fl to the shank 5 of theimproved breaching` tool generally designated 6. The Vbreaching tool 6is carried within a usual chuck 7 disposed within a chuck housing 8 ofthe drill.` As the specific construction of this rock drill does notenter into this invention, further detailed descriptionof the sameappears to be unnecessary.

The improved breaching tool 6 comprises a cylindrical body portion 9which serves to center andguide the broaching tool in the drill Ihol'ewill later tbe described. ,*Ihe body 9 'has formed thereon laterallypro- 'ectinff wings 10 of im roved form herein 23 C 3"preferablycalledfbat wings. 'The wings 10 are so constructedasftoienable:theibroaching tool to break away the rock in a moreeffective manner and to prevent bindingof the broaching tool in nthedrill hole. VAs illustrated, the wings 10have formed the-reon at theirlower sides vinclined flat percus sive `S.1.1.1^`a"0es 1.1 havinglateral shearing l edges'lQ.` The'flat surfaces 11 ofthe wings areherein `p refeiably formed 'at an angle lof forty-five degrees, ithaving been found that such `an vangle Iis most effective under theconditions encountered. vThe l"flat surfaces 11 terminate "inlateralshearing 'edges 12 which -converge outwardly and recedeyrearwardly .to ,meet 'in edges 13 which "form the lower edges ofparallel plane surfaces 14. The lupper surfaces 15 of the wings slopedownwardly to junctions with 'the lsurfaces 141 Aand `also are `'widestadjacent the body .of the tool. Thesurface's :14 are widestl at their,bottom edgesl `1,3 and the lateral edges of the surfaces 121 .and

"15 and the shearing edges l12 atv yeach v side of the bit lie inplanes, whereby the operation.

lateral surfaces 16 ofthe ,wings are A,plane surfaces wliichconvergeoutwardly and 'upwardly. v A

l,In the use of--the improvedbroachingtool it Vwillherein be noted thatafter series 'of:alined,.clo`sely spaced holes vA are drilled inthe rockaselearlyshown in Fig. o, the

kusualdrih bitis withdrawn "from the 'chuck 7 of .the hammer -drill andtheimproved broaching t'ool`6 substituted therefor, The operator theninserts ,the lower'portlon Iof the cylindricalbody ;9 ofthe breachingtool in one of the drill'holes A andthehaminer piston of .the impactmotor is then suitably actuated, causing the lstriking plug to nnpart aseriesof iinpact'blows to .the Vshank 5 ofthe tool'6 in a wellknownmanner. These hammer blowsonthe shank l o f'the',b'ro 'acl 1 ing `toolcause the flatbottom surfa'ees 11 of the bat wing to Yhave ,a,percussivefaetion' while Vthe lateral edges :12 have a 'shearing actionand 'consequently vthe partitions B between the adjacent holes are,effectively f'broken away as thedrilling machine "is -fed .downwardly.Thebodyfportion- 9 ofgthegbroach- `ing tool centers the 'tool in the,drill hole land -gu'ides y,the wings during 'the l,breaching theVbreachingl tool' iniV the hole dueV to" the V'piling up of dust andcuttings around the `VThe l,inclined ,Sides 16 ,Gf tha rwings formclearance for the infclinedeut.- .ting surfaces, ythereby'preventinggbinding ofVv tool. Furthermore, the tapered flat surfaces iof the wedge-shaped portions of the wings have a wedging action ony therock, thereby increasing the leffectiveness of the tool and theseinclined sides further reduce the tendency of theitoolito bindor'stiekinsthe holes.

7Afterthe lbreaching opera-tion is completed on the first set of holes,the broaching tool iis withdrawn and ii-nsertedyin the fnextjndj "wingswhereby "the effectivenessVl of `the 'f tool `is materially increasedand whereby alltfendency Vof the tool 'to bindorfstick in the iAholes isf'reduced to a minimum. ilt'willfurth'erbe noted that an improvedbroaching tool Iis 'provided of exceedingly simple `and `ruggedcharacter which may be [manufactured -vvith4 y,

facility andata minimum of expense. These fand "other advantages "ofvthe ,improved those skilled Qin 'this art.

'while i haveriauiis appueaeqnspeeieca ly"de`scribe d one lform which myinvention niay assume in practice, itpwill be underjstood `thatthis formofthel same isshown'for ,purposes :of illustration and ithat'the finvenltionjmaybe modified and embodied'gin various other fforms withoutdeparting lfromfits" spirit orthe scope of the appended claims.

i l"What Iclaimas'new` anddesire to secure by Letters Patent is:

[1. A b roaching toolv ofthe impact type comprising 'a shank having acylindrical" body portion fform'ing a-fguide, and jaflaterah lyAprojecting wing formedon saidbodypori tion, said wing 1fhaving -afper'oussive sul-face tapering outwardly :fand receding `rearwardily,anV upper surface likewise *tapering *outwardly but" sloping forwardly,an outer surface joining -saidfothe'r surfaces, and-lateral planesurfaces. a y

2. A broaching tool of the `impact -ltype comprising `a shank havi-nga'cylindrical"4 bo l portion forming -"a` guide, -rand a laterally project`ng` wingfforlned onsaid lbody portion, said wing v:having "a1"percussi-ve 'surface "tapering outwardly and receding *rearwardly, anupper surface tapering outwardlyand sloping forwardly, astraiglitoutersurface ldisposed parallel withthe longitudinallaxis of the tool joiningsaid inclined surfaces, and lateral plane surfaces.

8. A broa'ching Itool 1of comprising a :shank having -a cylindricalportion Vv,forming a lguide,1 and laterally fproj ecting wings ffor'medl on said tbody. fportion, said wings each having a, pereussive surfacetapering outwardly and receding the impact eyes:

rearwardly, an upper surface likewise tapering outwardly, an outersurface joining said other surfaces, and lateral plane surfaces.

4:. A breaching tool of the impact type 5 comprising a shank having acylindrical body portion forming a guide, and laterally projecting wingsformed on said body portion, said wings each having a percussivesurfacetapering outwardly and receding rearwardly, an upper surface likewisetapering outwardly, an outer surface tapering upwardly and joining saidother surfaces, and lateral plane surfaces.

In testimony whereof I affix my signature.

GEORGE H. RICHEY.

